import java.io.StreamTokenizer;
import java.io.IOException;

public class Add implements Transformation {

    /**
     * The integer value to add to each element of <code>args</code> for
     * this Transformation's operation.
     *
     * @see Add#transform
     */
    private int addValue;

    /**
     * Whether <code>addValue</code> has been properly defined during <code>
     * readArgs()</code>. If <code>false</code> then <code>transform()</code>
     * will do nothing.
     *
     * @see Add#readArgs
     * @see Add#transfrom
     */
    private boolean addDefined = false;


    /**
     * Creates a new Add transformation.
     *
     */
    public Add() { 

    }


    /**
     * Reads in the required arguments for this Transformation via the
     * StreamTokenizer, <code>s</code>. 
     * <p>
     * Add expects only one argument, mainly the integer value by which to 
     * increase each element of <code>args</code> during Add's transformation. 
     *
     * @param s          The StreamTokenizer from which this Transformation
     *                   will collect it's required arguments (if any).
     *
     * @see Add#transform
     */
    public void readArgs(StreamTokenizer s) {

	boolean error      = false;     // yes/no error occurred while reading 
	                                //  input

	try {

      DONE:
	while ( true ) {
	    
	    switch( s.nextToken() ) {

	      case StreamTokenizer.TT_NUMBER :

		  if ( addDefined )
		      error = true;
		  else {
		      addValue   = (int) s.nval;
		      addDefined = true;
		  }

		  break DONE;

	      case StreamTokenizer.TT_EOL    :

		  if ( addDefined == false )
		      error = true;

		  break DONE;

	      case StreamTokenizer.TT_EOF    :

		  if ( addDefined == false )
		      error = true;

		  break DONE;

	      default                        :

		  ////////////////////////////////////////
		  // Any data other than integer data is
		  // considered faulty.

		  error = true;

		  break DONE;
	    }
	}	    

	////////////////////////////////////////
	// If an error occurred then print help
	// message.

	if ( error ) {
	    addDefined = false;    // insure transform does not modify data
	    help( );
	}

	} catch (IOException e) {

	    System.err.println( "Error in input stream.");
	    System.exit( -1 );
	}
    }


    /**
     * Performs Add's transformation operation on <code>args</code>. Add adds
     * it's stored integer value to each element of <code>args</code> unless
     * an error occurred during <code>readArgs</code> in which case this 
     * transformation does nothing.
     *
     * @param args       The inputs to this Transformation's operation. The
     *                   elements of <code>arg</code> are modified by this 
     *                   operation.
     */
     public void transform( float[] args ) {

	 if ( addDefined )
	     for (int i = 0; i < args.length; i++)
		 args[i] += addValue;
    }

    
    /**
     * Returns information regarding the usage of Add.
     *
     */
    public void help() {
	System.out.println("Usage: Add <add value>");
    }
}